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Turbo Dropping Out - VGT Air Actuated


Go to solution Solved by Bill R,

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Posted

On my 180 mile trip today, at about mile 150 I lost all power.  Engine was still on, no warning light, and all engine specs within range.  I pulled over and called Frank McElroy who suggested a loss of turbo.  He was spot on.  Turbo pressure was zero.  

But after a few minutes, turbo started to work.  I get back on the road, but after a few miles, turbo drops out again.  I was able to keep moving as long as I didn't try to push it.  I could even maintain 50 mph.

For information purposes, I have the 400ISL, with the VGT that is electronically/air actuated.  The VGT has an air controlled mechanical actuator mounted on the turbo, see pic below.  The air to this is supplied via an electronically controlled valve from the ECM.  See pic below.

So I am now at my spot where the rig will stay for the next 2 months and I will begin to troubleshoot.  If anyone has had this happen, please let me know what you did to troubleshoot.  Here are the items I am going to be checking beginning tomorrow.  Please chime in on this journey with me.

1)  Check air supply to electronic turbo actuator control valve - I can only guess if I am loosing air the turbo will not work.

2) Check for air leaks on line from electronic turbo actuator control valve to the air controlled mechanical actuator on the turbo.  Again, loss of air may cause loss of turbo.

3) Test electronic turbo actuator control valve for functionality - this I have no idea how to do.  There are three ECM inputs (41,21,28) to this control valve.  I did not get any faults, so I am thinking this is not the problem.  But if the controller is not working to supply the correct amount of air, it could be. 

4) Disassemble the air controlled mechanical actuator on the turbo to see if there are any issues.  I am not sure how this mechanical controller works.  Any help out there?  I have posted a picture below.  The electronic actuators mounted on turbos are easy to take off to where you can then move a lever to check the function of the turbo spline movement.  But I have searched the internet and Quickserve to see how this air actuated mechanical actuator works and I can not finding anything.

5) If the above does not reveal any problems, then I will pull the turbo and inspect the internals for issues such as sticking splines or damage.  However, the more I think about how the turbo was responding, the more I am not thinking it is sticking.  There would be turbo power, and maintain, but as soon as I put a higher demand for power the turbo would drop out and take a little bit to recover. 

Thank you to anyone who has suggestions or confirmation of my plan of action.

 

Turbo Electronic Air Actuator.jpg

Turbo Mechanical Actuator.jpg

Posted

I have a different engine but your actuator looks similar in picture. If you have service manual for yours, it might say the same as mine, the electronic actuator is tested from Insite. There is also a waste gate actuator check referenced in the manual.

Screenshot_20221028_161059_Office.jpg

Posted
9 minutes ago, Ivan K said:

If you have service manual for yours, it might say the same as mine, the electronic actuator is tested from Insite.

Thank you Ivan, that does look like mine.  Frank M also gave me the Quickserve procedure for testing VGT pneumatic actuator (Procedure 45-010-113).

Now I have some procedures to start testing.  

 

Posted

Hello Bill, just out of curiosity, have you changed out the primary and secondary fuel filters? I had exactly what you are going through happen to me. Fortunately, I changed out these filters (I filled them with Diesel first) and thank the Lord it all got back to normal. Obviously the lack of fuel makes the Turbo feel and sound like it’s failed. I hope this works. Please keep us updated. Thanks!

 

 

Posted
7 minutes ago, MrAmbassador said:

Hello Bill, just out of curiosity, have you changed out the primary and secondary fuel filters?

Jorge, I did not, but that was my first thought.  However when I was having the issue of no power, when I would push down on the accelerator I would have a cloud of black smoke spewing out the tail pipe.  So to me that tells me that I am getting fuel but no combustion (no air from turbo).  I would be happy to be corrected if that assumption is wrong.  Changing the fuel filter and water separator would be an easy fix. ☺️

Posted
58 minutes ago, MrAmbassador said:

How about the Air filter, maybe it has not been changed out in a while???

Thanks Jorge, my fuel/water separator filters and air filter were changed out 10 months and 4,000 miles ago.  They should be good.  My DP guage for the air filter shows good too.

24 minutes ago, Ivan K said:

this is from Cummins troubleshooting tree:

Thanks Ivan, for my engine, 400ISL CM850,  Quickserve Air Handling Checks are STEP 5.  Which is what I will be doing first, but starting with Step 5D and the actuator function since my symptoms are immediate loss/gain (turbo boost) of power and not a continuous low or lack of power.   Please, please if anyone thinks I am barking up the wrong tree, let me to know.  Can a clogged fuel or air filter cause these symptoms?  i.e., sudden loss of all power boost (0 psi), and then recovers in about a minute.

STEP 5. Air handling troubleshooting procedures.  
  STEP 5A. Inspect the turbocharger blades for damage.  
  STEP 5B. Check the turbocharger axial and radial clearances.  
  STEP 5C. Determination of turbocharger type.  
  STEP 5D. Check variable geometry actuator rod for correct travel.  
  STEP 5D-1. Check for air leaks and inspect air lines.  
  STEP 5D-2. Check for air pressure at the turbocharger control valve outlet.  
  STEP 5D-3. Check for air pressure at turbocharger control valve outlet.  
  STEP 5D-4. Check for vehicle air tank pressure at turbocharger control valve inlet.  
  STEP 5D-5. Check for correct turbocharger actuator travel.  
  STEP 5E. Check for broken shaft inside the turbocharger.  
     
Posted

Don't know if you normally get any slight boost at idle and if it drops off as well, one more thing I might check would be throttle function. Otherwise I think you are on the right track, stuck or sticking VGT is not that unusual on Dodge trucks, same principle minus the air.

Posted

Hello Bill,

I had a very similar issue with my ISL 400 last year.  Short version... turbo output per the dash gauge wasn't normal.  Low pressure-excess pressure, pressure well in excess of throttle input, very intermittent operation.

Your picture shows the top portion of the actuator with a small air line attached which comes from the electronic pressure regulator.  Per the Cummins tech, the correct way to test the operation on the actuator was to: 1. disconnect the air line, 2. connect a regulated (i.e. adjustable) air line and dial in pressure while observing the movement of the rod from the actuator,  3. I seem to recall the measurement was supposed to be 10-11mm of movement measured at the turbo pivot post.  The tech tested mine and it would not move, nor could he pry the pivot in either direction.  This was a mobile tech in my driveway from a local Cummins shop.  His on site guess was the turbo was seized and needed to be replaced,  he had to return to the shop and work up a price list, parts delivery, etc.  I asked him, as long as the turbo has to come off, how about if I remove it?  He said sure-go ahead, will save you some labor time.  So i did, (that thing is heavier than it appears) got it on the work bench, started to remove the actuator and discovered the small rod end was seized onto the turbo lever shaft with corrosion.  Note, there is a small snap ring which keeps the actuator rod on the turbo shaft rod-- and its a real pain to remove while turbo is on the engine, you need to have a GOOD pair of angled snap ring pliers plus don't let it fly away.  Once i removed the actuator, the turbo control shaft worked freely with just one finger!!  H'mmm, I think the turbo itself is fine, so I ordered a new actuator, attached it to the turbo, bench tested the function and reinstalled the turbo assembly to the engine.   Success !!!  Turbo works as expected.  I later scheduled a chassis dyno test at Cummins shop which showed everything was within spec's.   If you've priced a new Holset VGT turbo, that's a scary number.

Important points:

1. Test the working function of the actuator properly while on the engine, including the air line from the electronic control unit to the top of the actuator to ensure it's not blocked.

2. If you need to (decide) to remove the actuator from the turbo to test the range of motion on the turbo control shaft itself prior to turbo removal ( i highly suggest that because there's several gaskets which will need to be replaced, plus several gallons of antifreeze) make sure you have good work lights, good quality offset snap ring pliers and a goodly portion of patience to get yourself into some position for access to that snap ring.  Note the top portion of the actuator, the arm and the small end will all need to stay in alignment, i.e. come straight off together.  

3. When you reinstall the actuator make sure you clean the small turbo pivot shaft well with some scotch brite, then use high temp grease on both the shaft and the actuator rod.  The instructions for the new one i purchased clearly show a grease fitting on the small end of the rod,  however, there wasn't any grease fitting actually on the rod..???   there is a small machined flat spot in the exact location, just no hole or fitting.  I do plan to remove the actuator, drill and tap it for a grease fitting,  I didn't at that time as we were scheduled to leave for the sunshine state and more of the white stuff was forecasted for the following day.

Hopefully that helps.  The explanation is longer than actually accomplishing the task.  It's just a bit challenging to get into the right spot for removal, some from the top and some from the bottom. 

Enjoy each adventure !!

John

 

 

  • Solution
Posted

SOLUTION FOUND!! - PROBLEM SOLVED!!

First the punch line, then I will step through the process of what I did to find it. 

The rubber boot connection to the turbo inlet was collapsing because of restricted air inlet flow caused by a compromised (reverse collapse) air inlet filter.

How did the air filter become compromised?   The air filter was changed out by a truck shop 10 months ago and only has 4,000 miles on it.  But......IT IS THE WRONG FILTER.  The air filter installed does not have the steel flex wrap, inside or outside.  Being a new coach owner at the time I didn't even question the new filter they installed.  Now I realize it is not the specified filter that requires a steel flex wrap both inside and outside.

Process of getting to finding the compromised air filter was long, but this is what happened.

1)  To ease my mind of a lack of fuel issue, I spinned off the H20 separator to inspect.  Slight amount of algae on two ports, but not much.  But I went ahead and replaced both the H20 Separator and Fuel Filter.

2)  Checked the axial movement of the VGT cone to make sure it was not stuck.  This was performed by looking at the pneumatic actuator rod that moves the external pivot lever that will axially move the VGT cone for the turbine.  Turning the engine on, pressurizes the pneumatic actuator from an electronic control valve with an air input line from the secondary tank PPV.  When engine was turned on I observed the pneumatic actuator fully engage the pivot lever that moves the internal cone for a minimum boost pressure (expected for startup).  So no issues found there.

3) Removed pneumatic actuator to check for sticking/range of movement for both the pivot lever and actuator.  There are several Quickserve procedures on how to do this, and it is important to follow because of air pressure that is need to be supplied externally for removal and operation.  Once the pneumatic actuator was removed, I was able to manually move the pivot lever on the VGT body back and forth with ease.  No sticking or restriction.  Applying external pressure to the pneumatic actuator resulted in full movement per specifications with out sticking also.  Actuator and lever were lubricated and actuator reinstalled leaving a pressure gauge on the actuator line.  So again, no issues found.

On 10/31/2022 at 2:23 PM, J & Di Cooper said:

Hopefully that helps.  The explanation is longer than actually accomplishing the task.  It's just a bit challenging to get into the right spot for removal, some from the top and some from the bottom. 

John - thank you for your input on this.  When you wrote this I was already in the throws of doing what you suggested, but it is great to see commonality in the process.  I didn't understand though your comment about antifreeze.  There was nothing involving coolant that I had to deal with.

4) Time for a test drive.  Started out great.  Running up to 65 mph in cruise and no boost issues.  AND THEN....loss of boost with black smoke.  WHAT???  Pulled over, and with the help of my BIL, mechanical engineer and aircraft mechanic who was helping me, we came up with a plan.  He would look at the pressure gauge while I drove, to see how the electronic control valve was modulating the pressure to the actuator.  Off we go, and as I accelerated my BIL saw the pressure fall as boost was need for increased speed.  Exactly as it should respond.  When I got to 55 mph I just gave it the gas, lost boost, and my BIL yells, I SEE THE PROBLEM.  He explained that the inlet boot to the turbo was collapsing, and thus we immediately knew we had some sort of air inlet issue.  Pulled over, and disconnected the rubber coupler on the filter outlet and slid it just slightly forward to allow for some air bypassing of the filter.  We were about 10 miles from our spot, so I drove back and had plenty of power with no boost lost.

5) Pulled out the air inlet filter and immediately saw the compromised filter on the outlet.  The element had somehow lost structural integrity and without a steel flex wrap it did not maintain its form and collapsed outward filing in the annular void where air would need to flow.   See pic below.  There is also a pic of what the correct element should look like with the steel flex wrap.

Lessons Learned -  Air filters need to be wrapped inside and outside in with the steel flex mesh and be only the specified ones in the manual.  If you have someone else changing your air filters, be absolutely sure they install the correct ones.  I will continue to do almost ALL work on the coach that I can.  Many shops out there do not know enough about our coaches.  I was trusting they did as a new coach owner. 

And many thanks to Frank McElroy who kept me on the straight and narrow in troubleshooting.

 

Pneumatic Actuator with Gauge.jpg

Compromised Air Filter.jpg

Compromised Air Filter.jpg

Air Filter with Flex Steel Wrap.jpg

  • Like 2
Posted

Thank you for posting the solution and how you went about the diagnostics.

I recall many years ago there were a lot of posts about filters being installed with air flow in the wrong direction.  I know the last few air filters I bought were bidirectional.  Something to pay attention to when buying or having shop install a new filter.

Posted

Hello Bill,

Good to hear you found the correct solution and in an inexpensive way also. Anyone with ISL having that style turbo actuator needs to consider greasing that rod/shaft connection occasionally.   The new replacement i purchased included instructions about lubing that connection, complete with a picture showing a zerk fitting on the bottom of the rod, but alas no actual fitting on the part...????

My comment about dealing with a couple gallons of coolant was only pertinent IF you also removed the turbo.

Choose to enjoy the journey!!

John

Posted

Did you drive in any downpours in that 4,000mi?

The steel mesh on both sides of the paper media on these Ecolite filters is a relatively new thing (maybe 5 or 6 years).

Not many had trouble with the older style with the mesh only on the inside, but, I have seen a pic of one with the paper media on it's way towards the turbo 😱!

Posted
50 minutes ago, 96 EVO said:

Did you drive in any downpours in that 4,000mi?

No downpours.  But the day of the failure we traveled 3 hours in a constant mist/light rain condition.  The filter was a bit damp and I figure may have contributed to the failure.   A mist/light rain may actually be worse than a down pour as the H20 droplets will be more susceptible to air flow dynamics.  I checked all of the intake piping and no issues with the intake and/or drain line.  It had to have been mist that was sucked into the filter housing.  No indications of water in the inlet piping to the filter.

Also, not only did the filter not have the mesh, it was smaller than the spec filter by 1 inch in diameter.  Accordingly this was a 20% reduction in flow capacity which may have also been a contributing factor.

55 minutes ago, 96 EVO said:

The steel mesh on both sides of the paper media on these Ecolite filters is a relatively new thing (maybe 5 or 6 years).

Thank you for this history.  Maybe the new design was an upgrade to prevent what I experienced?

 

Posted (edited)

Ah!

Windsor Bill had the same issue (6" inlet / outlet) on his '06 Windsor when he purchased it!

Your coach must have been going down the line alongside his, when they ran out of 7" something ( tubing, filters, adapters), and one of the installers must have made the executive decision..... "Ahhh, this should work just fine"!

Edited by 96 EVO
Posted
2 hours ago, 96 EVO said:

Windsor Bill had the same issue (6" inlet / outlet) on his '06 Windsor when he purchased it!

Wow!  @windsorbill06 and I communicate regularly since we do have the exact same coaches.  I PM'd him and below is his response.

"As you know, we got the coach new.  The flexible hose that goes from the upper intake, down to the filter came loose on one of our first trips.  It was dragging and got ruined. 
 
Under warranty, dealer ordered a new hose, per Monocos specs.  It came in and was too big.   That was my first clue something wasn’t right. 
Come to find out, whole air intake plumbing didn’t match to my owners manual, including filter.   It was too small..  Monaco stepped up and I got an entire new air intake system/filter under warranty. 
 
I met a guy in Quartzsite a couple years ago that had a similar Windsor.  His filter was the smaller size as well.    It seems to have been the norm."

 

I will be visiting my coach next week and begin to install the new larger spec'd filter.  I am sure I will have to install a 6"x7" coupler on both ends of the filter as the intake piping and the piping to the turbo are 6 inches.

As a side note, I recently had my ECM downloaded using Insite, and the lifetime MPG of the coach seemed to be lower than what I would expect.  I just read a post on IRV2 where the OP did research on air filter sizes for his coach and decided to increase the size of his filter from 6" to 7" inlet/outlet.  He installed the same filter as is spec'd for my coach, and he has the same engine too, 2006 400ISL.  He posted that his MPG went from 6,8 MPG to 7.8 MPG.  

So perhaps ALL this trouble has led to a solution that not only solves the problem, but rectifies a manufacturing assembly mishap and enhances MPG!!!  

Posted
3 hours ago, 96 EVO said:

The steel mesh on both sides of the paper media on these Ecolite filters is a relatively new thing (maybe 5 or 6 years).

And they market them as bi-directional for that reason. I still prefer to have the dust collected on its larger outside surface.

Posted
44 minutes ago, Ivan K said:

And they market them as bi-directional for that reason. I still prefer to have the dust collected on its larger outside surface.

I hear ya!

Harry Martin put together the necessary pieces to turn his filter and use it the way they were intended to be used!

Guest Ray Davis
Posted (edited)
1 hour ago, Ivan K said:

I still prefer to have the dust collected on its larger outside surface.

 

Hum, ya suppose it's really larger?  I see the idea that it would be but I figured the filter material started out flat ( each side equal ) then it was folded into it's accordian shape.  If that's the general process the inside & outside would be essentially the same, right? 

Edited by Ray Davis
Posted

Outside larger circumference, would have to have more area Ray.

1 hour ago, Bill R said:

   He posted that his MPG went from 6,8 MPG to 7.8 MPG.  

So perhaps ALL this trouble has led to a solution that not only solves the problem, but rectifies a manufacturing assembly mishap and enhances MPG!!!  

Yeah, you should be getting at least that.

I have an emission loaded engine, probably running heavier, and the extra drag of 2 more tires on the road, and I'm averaging 7.7mpg.

Posted
1 hour ago, Bill R said:

 

 

I will be visiting my coach next week and begin to install the new larger spec'd filter.  I am sure I will have to install a 6"x7" coupler on both ends of the filter as the intake piping and the piping to the turbo are 6 inches.

 

Double check before you order that coupler between the filter and turbo intake tube!

For some reason I think it may go down to 5".

Posted

Bill,

When Monaco re-did mine back in 2007, I don't have a reducer on the intake side of the filter.  That long flexible intake hose going up to the corner of the coach was replaced with  7".  When I replace my filter, that hose connects directly to the filter.

As Ben mentioned, Harry turned his filter end to end.  I've seen it in person and I know there are some pictures of it over on IRV2 somewhere.    When you do that, it actually pushes the filter back into that dead space, just aft of the radiator because the air coming out of the filter has to make an immediate 90 degree turn to get to the rigid pipe leading to the turbo.  

I'm getting ready to order a new filter.  The current one was installed about 4 years ago.  I plan on cutting it open just for fun and see how dirty it really is. 

BTW, I use 8 mpg for planning purposes, but actually getting a little better than than, without generator running.  

Posted
58 minutes ago, Ray Davis said:

 

Hum, ya suppose it's really larger?  I see the idea that it would be but I figured the filter material started out flat ( each side equal ) then it was folded into it's accordian shape.  If that's the general process the inside & outside would be essentially the same, right? 

Yes, that is correct.  The other thing to consider is air flow resistance.  You want the least number of turns and ideally you would want the filter media to see no localized area where dust would build up.  In my opinion, having air coming in from the end would allow for the most even distribution of air across the whole filter media with the least number of air flow turns.

Posted (edited)
3 hours ago, Ray Davis said:

 

Hum, ya suppose it's really larger?  I see the idea that it would be but I figured the filter material started out flat ( each side equal ) then it was folded into it's accordian shape.  If that's the general process the inside & outside would be essentially the same, right? 

Well, I think you've done permanent damage to my few remaining brain cell's , but your right! On a pleated filter, should be the same area inside & outside.

Still think the filter would work better flowing outside to in thou. Larger particles would drop off the media to the bottom of the can.

Inside to outside flow, every particle is blocking the media.

Edited by 96 EVO

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